Fix paper format: letter->a4

paper.tex

@@ -1,4 +1,6 @@
-\documentclass[journal]{IEEEtran}
+\documentclass[a4paper, journal]{IEEEtran}
+
+\usepackage[left=1.57cm,right=1.57cm,top=1.8cm,bottom=1.57cm]{geometry}
 
 \usepackage{amsmath,amsfonts}
 \usepackage{siunitx}
@@ -27,7 +29,7 @@
 \def\@maketitle{%
     \newpage
     \null
-    \vspace*{-4mm}
+    \vspace*{-3mm}
     \begin{center}%
         {\Huge \linespread{0.9}\selectfont \@title \par}%
         {\large \lineskip .5em%
@@ -36,7 +38,7 @@
             \end{tabular}
         \par}%
     \end{center}%
-    \vspace*{-8mm}
+    \vspace*{-3mm}
 }
 \makeatother
 
@@ -90,7 +92,7 @@
 
 \begin{document}
 
-\title{\vspace{-3mm}The Effect of the Choice of Hydration Strategy on
+\title{The Effect of the Choice of Hydration Strategy on
     Average Academic
 Performance}
 
@@ -129,8 +131,6 @@ of the Choice of Hydration Strategy on Average Academic Performance}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %
 
-\vspace*{-5mm}
-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%
 \section{Introduction}
 
@@ -172,7 +172,7 @@ strategy, for the behavioural measurement $113$ in total.
 \begin{figure}[H]
     \centering
 
-    \vspace*{-4mm}
+    \vspace*{-2mm}
     \begin{tikzpicture}
         \begin{axis}[
                 width=0.8\columnwidth,
@@ -198,7 +198,7 @@ strategy, for the behavioural measurement $113$ in total.
         \end{axis}
     \end{tikzpicture}
 
-    \vspace*{-3mm}
+    \vspace*{-2mm}
 
     \caption{Flow rate of the water dispenser depending on the
     hydration strategy.}
@@ -241,10 +241,11 @@ Fig. \ref{fig:Behavior}.
         \end{axis}
     \end{tikzpicture}
 
-    \vspace*{-3mm}
+    \vspace*{-2mm}
 
     \caption{Distribution of the choice of hydration strategy.}
     \label{fig:Behavior}
+    \vspace*{-1mm}
 \end{figure}
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%